Deck 3: Pharmacology of Local Anesthetic Agents

Question 1

What is the significant clinical difference between esters and amides?

A) Potential for allergic reactions
B) Cross-hypersensitivity
C) Lipid solubility
D) Drug potency

Answer 1

Potential for allergic reactions

Question 2

What does the membrane expansion theory of the action of local anesthetics suggest?

A) Anesthetics that are highly hydrophilic cause the matrix of the nerve membrane to expand, narrowing the sodium channels, thus preventing depolarization.
B) Anesthetics that are highly lipid soluble cause the lipoprotein matrix of the nerve membrane to expand, narrowing the sodium channels, thus preventing depolarization.
C) Anesthetics cause the sodium channels to expand, thus allowing the increase in protein binding within the channels.
D) All of the above

Answer 2

Anesthetics that are highly lipid soluble cause the lipoprotein matrix of the nerve membrane to expand, narrowing the sodium channels, thus preventing depolarization.

Question 3

Which component of the local anesthetic molecule improves the lipid solubility,which facilitates the penetration of the anesthetic through the lipid-rich membrane where the receptor sites are located?

A) Hydrophilic amino group
B) Intermediate hydrocarbon ester or amide chain
C) Lipophilic aromatic ring
D) All of the above

Answer 3

Lipophilic aromatic ring

Question 4

Why is lipid solubility an important characteristic of local anesthetic drugs?

A) A greater lipid solubility enhances the diffusion of the anesthetic drug through the nerve.
B) A greater lipid solubility indicates a higher potency of the anesthetic drug.
C) A greater lipid solubility allows for a lower effective dose of the local anesthetic drug.
D) All of the above.

Question 5

What does the specific protein receptor theory of the action of local anesthetics suggest?

A) The specific protein receptor theory suggests that anesthetics that are highly lipid soluble cause the lipoprotein matrix of the nerve membrane to expand, narrowing the sodium channels, thus preventing depolarization.
B) The method by which the impulses travel down the length of the nerve affects whether nodes of Ranvier are stimulated or not.
C) Displaced Ca++ and local anesthetic drugs compete to bind to receptor sites within the ion channels of cell membranes.
D) All of the above

Question 6

Local anesthetics are vasoconstrictors and decrease the absorption of the drug by the blood.

Question 7

The speed of recovery from local anesthetic is determined by the degree of binding to the receptor site of each anesthetic.

Question 8

Why is protein binding an important characteristic of local anesthetic drugs?

A) Increased protein binding allows more cations (RNH+) to bind to the receptor sites within the sodium channels, prolonging the presence of anesthetic at the site of action.
B) Increased protein binding allows more RN molecules to bind to the receptor sites within the sodium channels, prolonging the presence of anesthetic at the site of action.
C) Decreased protein binding allows more cations (RNH+) to bind to the receptor sites within the sodium channels, prolonging the presence of anesthetic at the site of action.
D) Decreased protein binding allows more RN molecules to bind to the receptor sites within the sodium channels, prolonging the presence of anesthetic at the site of action.

Question 9

Local anesthetics easily cross the blood-brain barrier.

Question 10

Which component of the local anesthetic molecule renders the molecule water soluble?

A) Hydrophilic amino group
B) Intermediate hydrocarbon ester or amide chain
C) Lipophilic aromatic ring
D) All of the above

Question 11

The most potent local anesthetic is bupivacaine which has the greatest degree of lipid solubility.

Question 12

Dissociation constant refers to which of the following descriptions?

A) Determines the portion of administered anesthetic dose in the lipid-soluble state (RN)
B) Determines the onset of anesthetic action as the increase of molecules crossing the nerve membrane decreases the time of the anesthetic's onset
C) The pH at which 50% of the molecules exist in the lipid-soluble form and 50% in the water-soluble form
D) All of the above

Question 13

The rate of systemic absorption of local anesthetics depends on the total dose,concentration,route of administration,vascularity of tissues,and presence or absence of a vasoconstrictor.

Question 14

What characteristic of local anesthetic drugs determines the speed of nerve recovery?

A) The concentration of the local anesthetic
B) The degree of lipid solubility
C) The degree of protein binding
D) The nonnervous tissue diffusibility

Question 15

Intravascular injections significantly increase the possibility of an overdose.

Question 16

Local anesthetics affect the CNS and CVS after biotransformation.

Question 17

Prilocaine is biotransformed in the liver only.

Question 18

Tachyphylaxis is a term used to describe what phenomenon?

A) An increased tolerance to a drug that is administered repeatedly.
B) If the dental procedure lasts longer than the duration of the anesthetic and the mantel and core fibers have fully recovered, the reinjection of local anesthetic will be ineffective.
C) Once the mantel fibers return to function, the patient experiences pain yet administration of anesthetic does not alleviate the pain.
D) All of the above

Question 19

If more anesthetic is needed for a procedure,it is important to reinject the anesthetic after the mantel fibers have fully recovered.

Question 20

The higher the pKa of an anesthetic,the faster the onset of action.

Question 21

Answer the following questions based upon the following case study.
Sam, a businessman who travels extensively, has been in your dental chair for 2 hours for extensive nonsurgical perio procedures. He insisted on having a long appointment in order "to get everything done at one time." A review of Sam's health history reveals that he is taking medications for high blood pressure; has no known allergies; recently quit smoking; and is a recovering alcoholic. He mentions that he is going through a divorce and that he is leaving for China within the week. You explain to Sam that, because of the long appointment and the amount of work that you need to accomplish, you will use a long-lasting local anesthetic to ensure his comfort. You apply topical benzocaine to all injection sites on the right side. You choose to administer the local anesthetic bupivacaine because of its long-lasting effect. Although Sam is a good-natured patient, you experience difficulty in achieving the desired level of anesthesia in order to keep Sam comfortable. Within 5 minutes of the administration of yet another cartridge of anesthetic, Sam begins to complain of a headache and you notice that he is slurring his words. You quickly retake his blood pressure only to discover that it has actually gone down since the beginning of the appointment. What thoughts should be going through your mind at this time?
Reflecting on your experience with Sam,what other factors may contribute to an incident similar to Sam's?

A) The use of topical anesthetics plus intravascular injections
B) An injection that is administered too rapidly
C) The perio infection and inflammation
D) All of the above

Question 22

Answer the following questions based upon the following case study.
Sam, a businessman who travels extensively, has been in your dental chair for 2 hours for extensive nonsurgical perio procedures. He insisted on having a long appointment in order "to get everything done at one time." A review of Sam's health history reveals that he is taking medications for high blood pressure; has no known allergies; recently quit smoking; and is a recovering alcoholic. He mentions that he is going through a divorce and that he is leaving for China within the week. You explain to Sam that, because of the long appointment and the amount of work that you need to accomplish, you will use a long-lasting local anesthetic to ensure his comfort. You apply topical benzocaine to all injection sites on the right side. You choose to administer the local anesthetic bupivacaine because of its long-lasting effect. Although Sam is a good-natured patient, you experience difficulty in achieving the desired level of anesthesia in order to keep Sam comfortable. Within 5 minutes of the administration of yet another cartridge of anesthetic, Sam begins to complain of a headache and you notice that he is slurring his words. You quickly retake his blood pressure only to discover that it has actually gone down since the beginning of the appointment. What thoughts should be going through your mind at this time?
Based on Sam's physical symptoms,what should you consider?

A) Sam is extremely relaxed and his blood pressure medication is working.
B) Sam is extremely stressed.
C) Sam may be experiencing a mild overdose to the anesthetic.
D) Sam may be experiencing a cardiovascular crisis.

Question 23

Which anesthetic drug has a short half-life of 45 minutes and is the least toxic of the anesthetics?

A) Articaine
B) Lidocaine
C) Mepivacaine
D) Prilocaine

Question 24

Answer the following questions based upon the following case study.
Sam, a businessman who travels extensively, has been in your dental chair for 2 hours for extensive nonsurgical perio procedures. He insisted on having a long appointment in order "to get everything done at one time." A review of Sam's health history reveals that he is taking medications for high blood pressure; has no known allergies; recently quit smoking; and is a recovering alcoholic. He mentions that he is going through a divorce and that he is leaving for China within the week. You explain to Sam that, because of the long appointment and the amount of work that you need to accomplish, you will use a long-lasting local anesthetic to ensure his comfort. You apply topical benzocaine to all injection sites on the right side. You choose to administer the local anesthetic bupivacaine because of its long-lasting effect. Although Sam is a good-natured patient, you experience difficulty in achieving the desired level of anesthesia in order to keep Sam comfortable. Within 5 minutes of the administration of yet another cartridge of anesthetic, Sam begins to complain of a headache and you notice that he is slurring his words. You quickly retake his blood pressure only to discover that it has actually gone down since the beginning of the appointment. What thoughts should be going through your mind at this time?
Why do you think Sam's blood pressure decreased from the beginning of the appointment?

A) Sam became more comfortable during the appointment.
B) Symptoms of a CNS and CVS overdose are biphasic.
C) Symptoms of a possible overdose change from a depression phase to a stimulation phase.
D) Some combination of the above

Question 25

Esters,benzocaine,tetracaine,and procaine are hydrolyzed in the plasma by the enzyme pseudocholinesterase and by liver esterases.Procaine is metabolized to PABA and is the major metabolic byproduct responsible for allergic reactions.

A) Both statements are true.
B) Both statements are false.
C) The first statement is true; the second statement is false.
D) The first statement is false; the second statement is true.

Question 26

What is the inability to hydrolyze ester local anesthetics and other chemically related drugs called?

A) Atypical pseudocholinesterase
B) Low hepatic dysfunction
C) Para-aminobenzoic acid intolerance
D) None of the above

Question 27

Which organs of the body will have higher concentrations of anesthetics?

A) High vascular organs
B) Low vascular organs
C) Brain, heart, liver, kidneys, lungs
D) Some combination of the above

Question 28

What factor/factors influence the duration of the effects of local anesthetics?

A) Degree of protein binding
B) Vascularity of injection site
C) Addition or absence of a vasoconstrictor
D) All of the above

Question 29

What is the purpose of adding a vasoconstrictor to the local anesthetic?

A) To increase the rate of absorption of the anesthetic
B) To reduce the rate of absorption of the anesthetic
C) To reduce systemic toxicity
D) To increase hemostasis

Question 30

What factor/factors determine the severity of an overdose reaction to local anesthetic?

A) Degree of drop in blood pressure
B) Time lapse between the administering of the local anesthetic to the overdose
C) Number of symptoms patient experiences
D) All of the above

Question 31

Answer the following questions based upon the following case study.
Sam, a businessman who travels extensively, has been in your dental chair for 2 hours for extensive nonsurgical perio procedures. He insisted on having a long appointment in order "to get everything done at one time." A review of Sam's health history reveals that he is taking medications for high blood pressure; has no known allergies; recently quit smoking; and is a recovering alcoholic. He mentions that he is going through a divorce and that he is leaving for China within the week. You explain to Sam that, because of the long appointment and the amount of work that you need to accomplish, you will use a long-lasting local anesthetic to ensure his comfort. You apply topical benzocaine to all injection sites on the right side. You choose to administer the local anesthetic bupivacaine because of its long-lasting effect. Although Sam is a good-natured patient, you experience difficulty in achieving the desired level of anesthesia in order to keep Sam comfortable. Within 5 minutes of the administration of yet another cartridge of anesthetic, Sam begins to complain of a headache and you notice that he is slurring his words. You quickly retake his blood pressure only to discover that it has actually gone down since the beginning of the appointment. What thoughts should be going through your mind at this time?
Considering Sam's health history,what anesthetic drug may have been a better choice?

A) Procaine
B) Articaine with epinephrine
C) Lidocaine
D) Mepivacaine

Question 32

Which part of the chemical structure of a local anesthetic determines the pattern of biotransformation of the anesthetic?

A) Lipophilic part
B) Hydrophilic part
C) Intermediate chain
D) All of the above

Question 33

What is another name for the elimination of the local anesthetic from the blood and tissues?

A) Tachyphylaxis
B) Dissociation constant
C) Half-life
D) Distribution barriers